Bacillus natronophilus sp. nov., an alkaliphilic bacterium isolated from a soda lake

Abstract

An alkaliphilic, moderately halophilic, heterotrophic, rod-shaped, spore-forming bacterium (M30^T) was isolated from a sediment sample collected from a soda lake (Lake Magadi, Tanzania). Strain M30^T was strictly aerobic, catalase-positive, oxidase-negative and non-motile. Growth occurred at 12-43 °C (optimum, 25-30 °C), at pH 8.0-12 (optimum, pH 9.5-10) and at salinities of 0.5-15 % (w/v) NaCl (optimum 5 %). It utilized various sugars and organic acids as sole carbon sources and was positive for amylase, cellulase, gelatinase, protease and xylanase activities. The cell-wall peptidoglycan contained meso-diaminopimelic acid and the polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified lipid and one unidentified phospholipid. The DNA G+C content was 48.9 mol%. The predominant menaquinone was MK-7 and the major fatty acids (>10 %) comprised anteiso-C_{15 : 0}, iso-C_{15 : 0}, and anteiso-C_{17 : 0}. Phylogenetic analysis based on 16S rRNA gene sequence affiliated M30^T to the genus Bacillus and showed the highest similarities to Bacillus populi FJAT-45347^T (96.4 %) and Bacillus aurantiacus K1-5^T (96.2 %). Based on the data from the current polyphasic study, M30^T represents a novel species of the genus Bacillus, for which the name Bacillus natronophilus sp. nov. is proposed. The type strain is M30^T (=JCM 32118^T=CGMCC 1.16739^T=MCC 3010^T).

Keywords: Bacillus natronophilus sp. nov; Bacillus sp; alkaliphile; moderately halophilic; soda lake.